IR: work around a bug in interface delegation descriptors

interface I {
        fun f(x: Int = 1)
    }
    class C(val y: I) : I by y {
        // implicit `override fun f(x: Int) = y.f(x)` has a default value for `x`
    }

-- the only case where a function with overridden symbols has defaults.

compiler/tests/org/jetbrains/kotlin/codegen/CompileKotlinAgainstKotlinTestGenerated.java

@@ -118,6 +118,11 @@ public class CompileKotlinAgainstKotlinTestGenerated extends AbstractCompileKotl
         runTest("compiler/testData/compileKotlinAgainstKotlin/defaultLambdaRegeneration2.kt");
     }
 
+    @TestMetadata("delegatedDefault.kt")
+    public void testDelegatedDefault() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/delegatedDefault.kt");
+    }
+
     @TestMetadata("doublyNestedClass.kt")
     public void testDoublyNestedClass() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/doublyNestedClass.kt");